In addition to cleaning, another highly desirable characteristic of personal cleanser/shower gel type compositions is to deliver consumer perceivable skin benefits from the compositions to the skin. One important way of achieving this result is through high deposition of emollient oils. In turn, this requires incorporation of high levels of oil into the cleanser/shower gel composition.
Unfortunately, dual cleansing and moisturizing compositions are difficult to formulate because cleansing ingredients, in general, tend to be incompatible with moisturizing ingredients. For example, emulsified oil droplets, especially hydrocarbon oil droplets, tend to phase separate from liquids during storage and form a separate layer at the top of the liquid cleanser. Furthermore, without an efficient deposition mechanism, oil droplets contained in the cleansing composition can be washed off from the skin by surfactants during the use of the product preventing the high deposition needed for perceivable skin benefit.
Another problem is that emollient oils often tend to depress foaming/lathering of cleansing ingredients. Further the best foaming cleansing surfactants also tend to be the least mild (i.e., they are irritating to the skin).
Accordingly, there is a need in the art for a composition which contains cleansing ingredients (which are both mild and capable of producing abundant lather) and which also can deliver moisturizing ingredients while remaining physically stable.
Liquid cleansers which can deliver skin benefit agents to provide some kind of skin benefit are known in the art. For example, one method of enhancing delivery of benefit agent to the skin or hair is using prehydrated cationic polymers such as Polymer JR.RTM. from Amerchol or Jaguar.RTM. from Rhone Poulenc. This method is disclosed, for example, in U.S. Pat. No. 3,580,853 to Parran et al, U.S. Pat. No. 5,085,857 to Reid et al., U.S. Pat. No. 5,439,682 to Wivell et al; or in WO 94/03152 (assigned to Unilever), WO 92/18100 (assigned to Procter & Gamble) or WO 97/48378 (assigned to Procter & Gamble).
In the patents noted above, to achieve oil deposition or skin conditioning effect the cationic polymers are premixed with an aqueous solution either with or without the presence of skin benefit agents to hydrate and dissolve the polymer before mixing with cleansing agents. Since they are dissolved, the cationic polymers are not visible even under a microscope. Dissolution of these cationic polymers in water is time consuming and costly, and can cause problems in processing, especially when a high level of cationic polymer is used in the composition in order to get high deposition of skin benefit agents. It is also known that liquid cleansing products containing high level of pre-dissolved cationic polymer is not desirable due to lower lather speed and slimy feel. Processing difficulties and undesirable in-use properties tend to prevent the use of high level of cationic polymer in the liquid cleanser to achieve high deposition of oils on to the skin.
Further, the art teaches that physical stability of the emollient oil cleanser system requires the presence of some sort of suspending or stabilizing agent other than cationic. U.S. Pat. No. 5,308,526 to Dias et al and U.S. Pat. No. 5,439,682 to Wivell et al, for example, teach the use of crystalline ethylene glycol long chain esters (e.g., ethylene glycol distearate) as suspension agent to prevent separation of oil droplets from the liquid. U.S. Pat. No. 5,518,647 to Zocchi teaches an emulsion system combining long chain ethoxylated alcohol, free fatty carboxylic acid and water soluble polymer to achieve physical stability of oil droplets in liquid cleanser. Another type of well-known suspension agents used to stabilize oil droplets in liquid cleansers are high molecular weight water-soluble polymers such as polyacrylate, modified celluloses and guar polymers as disclosed, for example, in WO 96/02225 (assigned to Unilever). Although these materials are effective for suspending oil droplets, they are expensive ingredients and, as is the case with cationic polymers, at higher levels they tend to cause difficulty in processing and to impart an undesirable slimy feel during the use of the product.
Without imparting negative effects on important cleanser properties (such as lather and in-use sensory properties) and its processability, applicants have found that storage stable liquid cleansers containing high level of oils (e.g., 1 to 30%, preferably 3 to 30% by wt.) and high level of cationic polymer (0.1 to 5%, preferably 0.3 to 5% by wt.) can be formulated using cleanser insoluble, water soluble cationic polymer particles as the stabilizer. In this invention, cleanser stability is achieved by structuring the liquid with particles of skin benefit agents themselves without the need for conventional thickeners.